Fig. 6

PQS present in the promoter region of UL2, UL24 and K15 gene forms G-quadruplex and regulates promoter activity. CD spectroscopy showing formation of G-quadruplex structures in oligonucleotides from the promoters of a UL2, b UL24 and c K15 genes in the presence ad absence of G-quadruplex binding ligands TMPyP4 (10μM) and BRACO19 (10μM); these genes were selected for functional studies. d Promoter activity of G-quadruplex containing promoter regions of pGL3-UL2, pGL3-UL24 and pGL3-K15 with and without BRACO19 as measured with a dual luciferase assay. e Promoter activity of G-quadruplex containing promoter regions of pGL3-UL2, pGL3-UL24 and pGL3-K15 with and without TMPyP4 as measured with a dual luciferase assay. The data presented in d and e show firefly luciferase levels (promoter activity) normalized with Renilla luciferase levels (internal control). A negative control, pGL3-NC (expression constructs with HHV-8 ORF50 promoter that does not contain G-quadruplexes) was also tested similarly. The addition of BRACO19 (10μM) and TMPyP4 (50μM) was linked to significant reduction in promoter activity of pGL3-UL2, pGL3-UL24 and pGL3-K15; but the gene expression from the negative control (pGL3-NC) was not influenced by the addition BRACO19 and TMPyP4. Experiments were done in in triplicate and average values are plotted. *denotes P < 0.005